The present invention relates in general to combination locks of the tumbler wheel type, and more particularly to tumbler wheel type combination lock monitoring systems for monitoring the condition of combination locks and producing an alarm signal at a remote location when the monitored combination lock is being manipulated or operated in an unauthorized opening attempt.
Conventional locks of the class known as combination locks usually comprise three or four tumbler wheels which are loosely journaled in a coaxial, side-by-side spaced stack for rotation whith a lock casing on a tubular arbor or tumbler post projecting inwardly from the front wall of the casing or from the rear cover plate. The lock dial, which usually has 100 peripheral calibration marks thereon, is affixed to a dial spindle which extends through the bore of the tumbler post and has keyed to the inner end thereof a disc-like drive cam which is likewise arranged coaxially with and spaced rearwardly from the stack of tumbler wheels. A drive pin projects forwardly from the drive cam and with a conventional fly rotatable through a limited arc and associated with the rearmost tumbler wheel, provides a lost motion coupling to drive the tumbler wheel in selected relation to the drive cam. A similar lost motion coupling is provided between each of the tumbler wheels so that they may be driven upon predetermined rotation of the drive cam. A thin spacer washer is also customarily provided between each of the tumbler wheels. Each of the flies or fly members between the successive tumbler wheels and between the rearmost tumbler wheel and the drive cam typically comprise a ring portion journaled in concentric relation with the associated tumbler wheel and a radial projection which lies between a pair of stop shoulders disposed to abut portions of the radial projection and limit angular rotation of the fly to about 20.degree. or other desired limited angular range. A drive pin or lug projects from the adjacent tumbler wheel into position to abut the radial projection of the fly and transmit rotation to the adjacent tumbler wheel after the fly has moved through its predetermined lost motion angular range. Each of the tumber wheels and the drive cam are provided with a peripheral notch or gate at a selected radial position on the drive cam and tumblers.
A fence lever which is pivotally connected near one end on a reciprocative bolt member slidably supported in the lock casing is provided with a depending nose near the opposite or free end of the fence lever which is designed to ride upon the drive cam periphery, in conventional combination locks, and has a bar or fence projecting laterally from the fence lever in overlying relation to the peripheries of the tumbler wheels. The position of the fence in relation to the length of the fence lever nose is usually such that the fence is spaced slightly outwardly from the peripheries of the tumbler wheels when the fence lever nose is riding on the drive cam periphery.
The combination lock is opened, in the case of such conventional combination lock structures, by rotation of the dial in a predetermined sequence in clockwise and counterclockwise directions through predetermined numbers of revolutions to a series of numerical positions indicated by alignment of numbers or indicia on the lock dial with a fixed index adjacent the lock dial periphery, to dial a predetermined series of combination numbers and thereby effect angular rotation of the plurality of tumbler wheels to positions which result in alignment of the tumbler wheel peripheral gates with the fence. The dial is then rotated to bring the drive cam gate to a position registered with the fence lever nose to cause the fence lever nose and fence to drop into the gates whereupon further rotation of the dial through a partial revolution in a predetermined direction achieves retraction of the bolt.
Also, combination locks have been provided with various types of guard or shielding mechanisms mounted on the drive cam to resist detection of the combination by the "feel" of the points of engagement of the fence lever nose with the driving cam gate in accordance with well-known lock manipulation procedures to resist opening of the lock by unauthorized persons who do not have authorized knowledge of the combination to which the lock has been set. Descriptions of such locks designed to defeat unauthorized detection of the lock combination are found in prior U.S. Pat. Nos. 2,575,674 and 2,807,954 as typical examples.
In especially sensitive high security locations designed to be protected by such tumbler wheel type combination locks, it is frequently desirable to be able to continuously monitor the condition of the combination lock protecting a security area or security container and provide a signal at a remote location or security monitoring station when a combination lock is undergoing attempted opening manipulation or operation at times when such lock operation is not authorized. Heretofore, various combination lock and push button lock systems have been proposed involving electrical switch arrangements associated within them to detect operation of the lock and provide a signal at a remote monitoring location indicating lock operation. Examples of these are found in U.S. Pat. Nos. 1,711,780 to Findlay, 2,855,588 to Allen, 1,871,303 to Chesick, and 726,254 to Carlton. Also, photocell light sensor systems assocatied with a rotary cylinder type key lock have been proposed in U.S. Pat. Nos. 3,889,501 to Fort, 3,749,930 and 3,845,362 to Roe, and 3,764,859 to Wood. However, none of these meet the requirements desired for a tumbler wheel type combination lock wherein components of the tumber wheel type combination lock are continuously monitored during a security period to detect movement of various components of the combination lock indicating attempted opening manipulation of the lock, which can provide reliable signals at remote monitoring stations to advise monitoring personnel of an authorizied operation of the lock.
An object of the present invention, therefore, is the provision of a novel tumbler wheel type combination lock system having light sensing means for monitoring the position of a plurality of components or portions of the combination lock and producing an alarm signal at a remote location when movement of the monitored combination lock components or portions occurs.
Another object of present invention is the provision of a novel and highly reliable light sensing and electrical signalling system in conjunction with tumbler wheel type combination locks for monitoring the position of various components of the lock and generating alarm signals at remote locations signifying unauthorized attempted operation of the lock.
Other objects, advantages and capabilities of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings illustrating a preferred embodiment of the invention.